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Articulations
Articulation
Joint between bones
Does not mean movement!
Some joints are immovable; sutures.
Classification of joints
Two questions about joints:
1- How does it move? - functional
2- How is it held together?- structure
I) Functional definition "
1)synarthrosis"
! Immovable joint; sutures!
2)amphiarthrosis"
! Partially movable; fibula and tibia (syndesmosis).
3)diarthrosis
Freely moveable; knee, shoulder, fingers.
II) Structural definition
Structure of the joint; how the joint is held together.
1)fibrous"
Lots of collagen fibers, usually dense CT; limited or no movement.
!
a) sutures"
Skull- fibers anchors bone.!
!
Fontanelslarge areas of CT between fetal cranial bones.
!
Synostoses
Synostoses; Sometimes sutures fuse!
No joint present- only bone.
b) syndesmoses"
!More fibrous CT, longer fibers!
Similar to ligaments!
!Slight degree of motion; amphiarthrotic.!
!Tibiofibular joint.
c) gomphoses
Very dense CT layer!
Between the alveoli of alveolar processes and teeth. !
Synarthrotic.
2) Cartilaginous
Cartilage within the joint
a)synchondrosis"
! Temporary cartilaginous joint!
! During the growth phase. !
Immovable joint; epiphyseal plate.
!
b)symphysis
Cartilaginous pad; between the two pubic bones.
3) synovial
Complex structure, diarthrotic. !
Joint cavity filled with synovial
fluid.
Structure
A) articular capsule"
!
Surrounds the joint and
cavity.!
!
Consists of...
!
a) outer fibrous" capsule
Irregular
dense CT, very
!
fibrous; collagenous. !
!
External
sheath; holds joint
together.
!
b) inner synovial membrane
Lines the inside of the fibrous capsule !
Boundary of the synovial cavity.!
Produces synovial fluid.
B) joint cavity"
!Fluid filled; between the bones of the joint."
!Free movement; protection of joint.
!
Synovial fluid
Fluid secreted by synovial membrane."
Lubricating, nutrient rich material."
Protects and maintains hyaline cartilage of the epiphyses
C) accessory ligaments"
!Additional mechanical support to the joint.
a) extracapsular ligaments"
!
Located outside of the joint capsule.
!
b) intracapsular ligaments
Help stabilize the joint internally.
D) articular discs"
!Discs of fibrocartilage"
Shape the internal surface of joint"
!Better fit between the bones.
intra-articular discs or menisci"
!
Within the knee joint
!
E) bursae
Fluid filled sacs, cushion underneath ligament and
tendons."
Where the joint might experience extra stress or
pressure.
Factors that allow some movement
1) apposition of parts"
!
Soft structures limit how much a joint can move.
2) fit of structures"
!
How bones fit together; defines the range of motion.
3) strength and tension of ligaments"
!
…determines range of motion.
4) arrangement and tension of muscles
…determines range of motion."
Also help stabilize the joint.
1) gliding
Movements
Bone “slides’ over the surface of another.
No change in angle.
2) angular
! Motion defined by a change in angle
a) flexion/extension
!
Decrease in angle, flexion; increase, extension.
b) abduction*
!
Limb is moved away from the midline.
c) adduction*
!
Limb is moved towards the midline.
d) rotation
!
Rotates around a axis
e) circumduction
Complex series of motions combined into a
single smooth motion"
Pitcher winds up to pitch a ball.
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3) special"
a) inversion/eversion"
The foot; inversion- sole of the foot faces midline."
! Eversion- sole of the foot faces laterally
b) dorsiflexion/plantarflexion"
!
Foot; dorsiflexion- flexing the foot towards the shin."
Plantarflexion- extending the foot towards the floor.
c) protraction/retraction"
!
Structure is pushed out- protraction, or pulled in- retraction
d) supination/pronation"
!
Turning the palm to face anteriorly, supination."
Turning the palm to face posteriorly, pronation.
e) elevation/depression
Raising or lowering a structure, respectively.
Types of joints
Types of movement a joint can produce
1) gliding- arthrodial"
2) hinge-ginglymus"
! Flexion/extension
3) pivot-trochoid
Rotation
"
!
4) ellipsoid- condyloid"
Flexion/extension and abduction/adduction
!
5) saddle- sellaris"
! Flexion/extension and abduction/adduction
6) ball & socket- spheroid
Flexion/extension, abduction/adduction and rotation
Planes of movement
Joint movement creates planes of movement
Nonaxial"
No angular change; gliding, arthrodial joint
!
Monaxial"
Change along one axis; flexion/extension; ginglymus joint
!
Biaxial"
Two axes; flexion/extension and abduction/adduction;
!
condyloid
and sellaris joints
Triaxial
Three axes; flexion/extension, abduction/adduction and
rotation; spherical joint.
Tibiofemoral joint
Knee joint
3 joints"
Largest and most complex in the body
!
intermediate patellofemoral"
!Between patella and femur.
lateral tibiofemoral"
! Between lateral condyle of femur and tibia.
medial tibiofemoral
Between medial condyle of femur and tibia.
articular capsule
Capsule of the knee is not complete. Does not entirely surround the structures of the knee.
extracapsular ligaments"
!
Knee ligaments; external support.
patellar ligament"
Anterior surface of the knee; inferior margin of patella to tibial tuberosity.
!
tibial collateral ligament*"
Medial surface of the knee; medial epicondyle of femur to the medial side of
! head.
tibial
fibular collateral ligament
Lateral surface of the knee; lateral epicondyle of the femur to the lateral side
of fibular head.
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Intracapsular
Within the knee capsule
Anterior cruciate*"
!
!Anterior side of the joint cavity."
Prevents the femur from sliding
!posteriorly
!
Posterior cruciate
Posterior side of the joint cavity. "
Prevents the femur from sliding anteriorly
articular discs"
!Cartilaginous pads within the capsule;
!stabilize the fit of the bones.
!
medial meniscus*"
! the medial condyle of tibia;
On
! with the medial femoral
fits
condyle.
!
!
lateral meniscus"
!
!
!
!
On top of the lateral condyle of
tibia; fits with the lateral femoral
condyle.
*involved in injuries by lateral blow to the knee